Here's a breakdown of what's involved, and strongly recommend having a professional HVAC technician perform this conversion. Attempting this yourself without the proper knowledge and tools can be dangerous and costly.
Necessary Steps for R-12 to R-134a Conversion:
1. Oil Change: R-12 uses mineral oil, while R-134a requires PAG (polyalkylene glycol) oil. The old mineral oil must be completely flushed out and replaced with the correct PAG oil compatible with R-134a. This requires specialized equipment to ensure complete evacuation.
2. O-ring Replacement: R-134a has different compatibility with seals and O-rings than R-12. All O-rings in the system, particularly those in the compressor, accumulator, and expansion valve, should be replaced with new ones designed for R-134a.
3. Expansion Valve/Orifice Tube Check: The expansion valve or orifice tube (depending on your system) might need to be replaced or adjusted. These components regulate refrigerant flow and may not be optimal for R-134a.
4. Compressor Compatibility: While some R-12 compressors *might* work with R-134a and PAG oil, it's not guaranteed. A failing compressor is a common outcome of improper conversion. Assessment by a professional is crucial.
5. Vacuum and Charging: After the oil change and seal replacement, the system needs a thorough vacuum to remove any remaining moisture and air. Then, it must be charged with the correct amount of R-134a refrigerant. This requires specialized gauges and equipment to measure pressure and temperature accurately.
6. Leak Detection: A leak detection test is crucial before and after the conversion to ensure the system is airtight. Leaks are common during the conversion process due to old and brittle components.
What you'll need (beyond basic tools):
* Refrigerant recovery and recycling machine: This is absolutely essential for environmentally responsible handling of R-12. It's illegal to vent R-12 into the atmosphere.
* Vacuum pump: To evacuate the system before charging.
* Refrigerant charging scales/manifold gauge set: To accurately measure and charge the system with R-134a.
* PAG oil: The correct type and amount specific to your system.
* O-rings and seals: Specifically designed for R-134a.
* Possibly a new expansion valve or orifice tube.
* Possibly a new compressor.
In Summary: Retrofitting your AC system is a complex and potentially expensive process. The cost of parts and labor could easily exceed the value of your vehicle if numerous components require replacement. It's highly recommended to consult a qualified HVAC technician experienced in R-12 to R-134a conversions. They have the necessary equipment, expertise, and knowledge to ensure the conversion is done safely and correctly. Attempting this yourself risks damaging your system, voiding any warranties, and possibly injuring yourself.
